Prediction of spectacle-corrected visual acuity using videokeratography.

Purpose: Our aim was to improve prediction of spectacle-corrected visual acuity (SCVA) using indices derived from the EyeSys System 2000 data (version 3.1).

Methods: We studied corneal topography in 182 eyes from 8 groups of patients. Holladay Diagnostic Summary indices were recorded. Nine statistical indices calculated with the first 8-ring data and refractive power symmetry index were also studied. Correlation with SCVA (LogMAR units) was studied by means of Pearson's regression. Multiple linear regression was used to obtain linear equations combining several indices.

Results: At a univariate level, total astigmatism cylinder showed the strongest correlation with SCVA (r = .63, P = .0001). At a multivariate level, the predicted visual acuity obtained by linear equation combining the asphericity coefficient, the predicted corneal acuity, the mean of the means, and the total astigmatism cylinder was closely associated with SCVA (r = .72, P = .0001). It was identical to SCVA in 58.2% of the cases, within one line in 75.8%, and within two lines in 91.2%.

Conclusion: Multiple linear regression resulted in the best prediction of spectacle-corrected visual acuity, giving notable improvement in prediction of spectacle-corrected visual acuity as compared to the predicted corneal acuity available in the EyeSys System 2000.